This invention relates to injectors for injecting fluid into living organisms.
In many medical environments, a medical fluid is injected into a patient during diagnosis or treatment. One example is the injection of contrast media into a patient to improve CT, Angiographic, Magnetic Resonance or Ultrasound imaging, using a powered, automatic injector.
Injectors suitable for these and similar applications typically must use a relatively large volume syringe and be capable of producing relatively large flow rates and injection pressures. For this reason, injectors for such applications are typically motorized, and include a large, high mass injector motor and drive train. For ease of use, the motor and drive train are typically housed in an injection head, which is supported by a floor, wall, or ceiling mounted arm.
The injection head is typically mounted on the arm in a pivotal manner, so that the head may be tilted upward (with the syringe tip above the remainder of the syringe) to facilitate filling the syringe with fluid, and downward (with the syringe tip below the remainder of the syringe) for injection. Tilting the head in this manner facilitates removal of air from the syringe during filling, and reduces the likelihood that air will be injected into the subject during the injection process. Nevertheless, the potential for accidentally injecting air into a patient remains a serious safety concern.
In addition to the injection head discussed above, many injectors include a separate console for controlling the injector. The console typically includes programmable circuitry which can be used for automatic, programmed control of the injector, so that the operation of the injector can be made predictable and potentially synchronized with operations of other equipment such as scanners or imaging equipment.
Thus, at least part of the injection process is typically automatically controlled; however, the filling procedure, and typically some part of the injection procedure, are normally performed by an operator, using hand-operated movement controls on the injector head. Typically, the hand-operated movement controls include buttons for reverse and forward movement of the injector drive ram, to respectively fill and empty the syringe. In some cases, a combination of buttons is used to initiate movement of the ram or to control ram movement speed. The injector head also typically includes a gauge or display for indicating injection parameters to the operator, such as the syringe volume remaining, for the operator""s use when controlling the injector head.
In many cardiology procedures, cardiologists often prefer to use hand-held syringes to administer contrast media to a patent whereby the cardiologist can xe2x80x9cfeelxe2x80x9d the injection and carefully control the rate of injection as needed. Because a high pressure is required to push contrast media through a catheter, small hand syringes must be used if an operator desires to manually administer the contrast media. However, these small syringes must be refilled several times during the contrast injection procedure, thereby increasing the risk of introducing air into the syringe or catheter.
U.S. Pat. No. 6,221,045 to Duchon et al. discloses a hand-held remote which may be used to control the injection of contrast media with a powered injector. If an operator chooses to use a powered injector having conventional controls, the operator must rely on visual indicators from the injector to determine how to manipulate the control for optimum injection. The visual indicators typical of current injector systems do not provide operators with the physical sensing of the injection that they prefer. Thus, one drawback of current injector systems, including the hand-held control system of Duchon et al., is that they do not permit operators to physically sense the injections and thereby control the rate and volume of the injection.
Due to sterility requirements in medical environments, hand-held controls are typically provided as disposable items. Thus, another drawback of conventional hand-held controls which utilize electronic or digital signals to control the injections is that they are not disposable without prohibitive expense.
A need exists for a hand-held remote which may be used with a powered medical injector to control the injection of contrast media while providing tactile feedback to the operator and which solves various problems in the art, such as those mentioned above.
The present invention provides a simple and convenient means for remotely controlling the injection or aspiration of fluids into or out of a patient using a medical fluid injector while providing tactile feedback to the user of the medical fluid injector. In an exemplary embodiment, a hydraulic remote for use with a medical fluid injector includes a syringe with a plunger slidably disposed within the syringe body, a pressure transducer which may be coupled to the control circuit of a medical fluid injector, and a conduit which connects the syringe to the pressure transducer. As used herein to describe the remote, the term xe2x80x9chydraulicxe2x80x9d refers to the use of a fluid, which may be a liquid or a gas. Accordingly, the hydraulic remote could also be described as a pneumatic remote. Movement of the plunger into and out of the syringe body causes a change in pressure within the syringe body. The pressure transducer senses this change in pressure through the conduit and the control circuit of the medical fluid injector responds to the change in pressure by injecting or withdrawing fluid from the patient. The pressure in the syringe may also be sensed by the user of the hand-held remote such that the remote provides a tactile feedback to the user that is indicative of the rate and volume of injection or aspiration. The syringe and conduit may be inexpensive, off-the-shelf items, thereby minimizing disposal and replacement costs.
In another exemplary embodiment, a medical fluid injector includes a hydraulic remote, as described above, and further includes a plunger drive ram, a motor for moving the drive ram, a second syringe attached to the injector. The plunger drive ram moves a plunger into and out of the second syringe to inject or aspirate fluid from a patient. The medical injector further includes a control circuit which controls the movement of the plunger in the second syringe and responds to pressure sensed by the pressure transducer to move the plunger drive ram into or out of the second syringe. The medical injector responds to an increased pressure sensed by the pressure transducer by moving the plunger drive ram at a rate related to the change in sensed pressure from the hydraulic remote.
In another exemplary embodiment, a medical fluid injector includes a hand-operated control mounted to the injector. A control circuit of the injector responds to movement of the hand-operated control to move a plunger drive ram into or out of a second syringe attached to the medical injector at a rate corresponding to movement of the hand-operated control. The medical injector further includes a hydraulic remote and the control circuit is configured to respond to actuation of the hydraulic remote or the hand-operated control by moving the plunger drive ram into or out of the second syringe.
In yet another exemplary embodiment, the medical injector further includes a second pressure transducer coupled to the control circuit and to the hydraulic remote. The control circuit responds to pressure sensed by the first pressure transducer to control the motion of the plunger drive ram into or out of the second syringe. The control circuit responds to the pressure sensed by the second pressure transducer to enable operation of the medical fluid injector when the pressure transducer senses a pressure above a preset threshold. Advantageously, the threshold pressure is set at a level such that injection or aspiration of fluid will cease when a user releases the plunger on the hydraulic remote.
In another exemplary embodiment of the present invention, a circuit board is couplable to an existing medical fluid injector to modify the injector so that it can be used with the hydraulic remote as described above.
In yet another exemplary embodiment, a method of controlling the injection or aspiration of fluid using a medical fluid injector having a hydraulic remote coupled to the injector includes the steps of moving a plunger of the hydraulic remote to generate a pressure, sensing the pressure generated by the hydraulic remote, and moving a plunger drive ram on the injector in response to the sensed pressure.
The features and objectives of the present invention will become more readily apparent from the following Detailed Description taken in conjunction with the accompanying drawings.